Question

I really hope someone can help me with this. I’m struggling with it for nearly two days now…

I have a DB-table “Device” and a table “Connection”. I’m using it to visualize my company’s network. To pass the data to the JS-framework I use to visualize the data I need an array like this:

Array
(
    [id] => 1
    [name] => TestPC1
    [children] => Array
        (
            [0] => Array
                (
                    [id] => 2
                    [name] => Testhub 2
                    [data] => Array
                        (
                        )

                    [children] => Array
                        (
                            [0] => Array
                                (
                                    [id] => 3
                                    [name] => Rack3
                                    [data] => Array
                                        (
                                        )

                                    [children] => Array
                                        (
                                        )

                                )

                            [1] => Array
                                (
                                    [id] => 4
                                    [name] => Rack4
                                    [data] => Array
                                        (
                                        )

                                    [children] => Array
                                        (
                                        )

                                )

                        )

                )

        )

)

The device-table looks like this:

A     |     B
-------------------
1     |     2
2     |     3
2     |     4

The visualization of this example looks like this:

http://img34.imageshack.us/img34/4230/netmd.jpg

Does anyone have an idea, how to get from the db-data to this array?

Thank you.

Answer 1

Let’s say you want to do it in PHP using that table, for example’s sake I’ll use an array to represent the returned database data after a JOIN between the given table and what I imagine is an ID->Name mapping table:

$links = array(
    array('A' => 1, 'AName' => 'TestPC1', 'B' => 2, 'BName' => 'TestHub2'),
    array('A' => 2, 'AName' => 'TestHub2', 'B' => 3, 'BName' => 'Rack3'),
    array('A' => 2, 'AName' => 'TestHub2', 'B' => 4, 'BName' => 'Rack4')
);

$elements = array();

// Build the tree
foreach ($links as $link) {
    if (!isset($elements[$link['A']])) {
        $elements[$link['A']] = array(
            'id' => $link['A'], 'name' => $link['AName'], 
            'data' => array(), 'children' => array()
        );
    }
    if (!isset($elements[$link['B']])) {
        $elements[$link['B']] = array(
            'id' => $link['B'], 'name' => $link['BName'], 
            'data' => array(), 'children' => array()
        );
    } 
    $elements[$link['A']]['children'][$link['B']] = &$elements[$link['B']]; 
}

// Patch up the indices to start from 0
foreach ($elements as &$element) {
    $element['children'] = array_values($element['children']);
}

$elements = array_values($elements);

Personally I wouldn’t bother patching up the indices, it will make it easier searching for entries by ID later if you don’t.

Be careful when entering your parent/child data or you’ll wind up with a lovely circular reference.

You will of course need to replace the references to $links with a suitable db command that produces an array (mysql_fetch_array etc).